THE ADAPTATION OF NATURAL (GEOLOGICAL) BARRIERS FORRADIOACTIVE LILW NEAR SURFACE DISPOSAL IN ROMANIA

摘要

According to the Minimum Disturbance (MD) Design philosophy (as stated by Dr. Carl-OlofMorfeldt, Mineconsult-Sweden), it is a good practice to proceed with a significant knowledge ofgeology in order to adapt engineering approaches to nature; in fact, this is considered to be afundamental principle. The geological setting for a waste disposal site is the starting point for bothdefining current in situ conditions and predicting the future conditions. This paper describes how theRomanian radioactive waste disposal program was implemented for low and intermediate level wastes(LILW). The selection process for LILW disposal at the near surface included 37 potential sites 3candidates sites →2 candidates sites →1 preferred site – Saligny, which is near to the main wasteproducer, the Cernavoda Nuclear Power Plant (NPP). Geological criteria were established at thebeginning of the selection process: lithological, petrographical, tectonical, seismological,hydrogeological, geotechnical, etc. To select a preferred site, the adequacy of transport facilities andpublic acceptance criteria were also used. Safety analyses were done to predict the future behavior ofthe geological barrier – a thick unsaturated zone including red clay with, mainly, a smectiticmineralogical component – with use of specific software, SUTRA, SWMS – 2D, and CHAIN – 2D.In both of the candidate sites, Cernavoda and Saligny, the maximum extension of the contaminantH3 remains inside of the red clay barrier and well above the main aquifer of the Cernavoda area, which ishosted in Barremian limestone. Geoengineering works are planned to improve the upper soil layer (loess)properties with respect to wetting sensibility and erosion by compacting and treating with differentadmixtures (cement, bentonite, consolid etc.) and by locating the site in a minimum wetting compressibilityarea. At the same time, an additional barrier will be added to integrate the site conditions at time ofconstruction. In addition, the determination of specific radionuclide migration parameters for actual sitesamples was accomplished for estimating the contamination risk values. The main objective in this flexibleRomanian design was to minimize the disturbance of pristine geological settings and the need for largescaleengineering barriers as much as reasonable possible.